10 Things to Know Before Trying the Whole30 Diet

Created by Melissa Hartwig (and her then-husband) in 2009, the Whole30 diet is a 30-day plan that eliminates food groups Hartwig claims are “psychologically unhealthy, hormone-unbalancing, gut-disrupting [and] inflammatory.”

However, US News & World Report ranked it 37 out of 40 on its list of Best Diets (compared to number 1 DASH), in part because there is no scientific research to back up the claims about the plan. Here’s what registered dietitians want you to know before starting Whole30.

With no sugar, dairy, grains, alcohol, beans, legumes or preservatives like carrageenan, MSG and sulfites, “Whole30 offers a way to step back and take a look at what types of food you are really eating,” says Sidney Fry, RD and James Beard award-winning food and nutrition author. “It cuts out boxed, processed fare and makes you truly focus on foods in their whole, natural form.” By reading labels and learning about what you’re really eating, you may decide to make some changes even if you don’t continue the Whole30 plan.

“By cutting out certain foods, you might notice which ones negatively affect you the most,” says Mascha Davis, MPH, RDN. Any signs something is off — an upset stomach, bloating, gas, fatigue, headaches, etc. — could mean it’s better for you to continue avoiding that food. Still, it’s best to consult a doctor or registered dietitian if you’re concerned about any food sensitivities or allergies.

“This program relies heavily on meal prepping and does not lend itself well to being caught off guard, which can be a problem if you travel a lot,” says Fry. She suggests keeping snacks such as nuts, hard-boiled eggs and apples with packets of almond butter on hand at all times.

The Whole30 plan bans sugar and artificial sweeteners. And while you can find recipes for compliant desserts online, those aren’t meant to be enjoyed nightly. If you crave something sweet, a piece of fruit (maybe with some almond butter) is recommended. “It may take a few days of effort, but your taste buds will slowly start to become more sensitive to sugar, and you may even start to crave it less,” Fry says.

Not everyone experiences a “reset” in their taste buds and cravings, unfortunately. Moreover, “This diet is unlikely to build healthy, sustainable habits,” Davis says. “Anytime there is a lot of restriction, that tends to be counterproductive and can cause people to overeat or even binge on the foods they are missing.”

Once the 30 days are over, you may maintain some of the positive changes to your diet, but it’s more probable that you revert right back to your original eating habits — or you could even go hard on the ice cream and cocktails you’ve been avoiding. “Whenever people go back to eating normally after restricting, they tend to regain weight,” Davis explains.

“Many people complain of experiencing hangover or flu-like symptoms or simply just feeling off,” notes Fry. Headaches, fatigue and mood swings are common in the early days of the program, according to the Whole30 timeline.

Beans, whole grains, soy and dairy provide nutrients such as fiber, iron, zinc, phytochemicals, protein, vitamin D and calcium. “Cutting all of these out can cause imbalances. You might lack essential nutrients if you cut out all of those food groups,” Davis says. Talk to your doctor or a registered dietitian to see if you should consider taking any supplements if you decide to do Whole30.

“It’s almost impossible to go out with friends and enjoy restaurant meals on the Whole30 diet,” Davis says. That’s because it’s difficult to find items on menus without sugar, grains, legumes, dairy, carrageenan, MSG and sulfites, and you’ll likely have to ask lots of questions. Since alcohol is banned, it’s probably better to turn down happy hour invites for the next month and find a supportive community online.

What happens after 30 days? “If you’re feeling great, it’s often unclear as to how or when you should start eating some of the foods you’ve eliminated,” Fry says. “If you choose to continue to avoid these foods, there’s less guidance on how to structure your diet to make sure you’re getting enough fiber, zinc, iron, vitamin D and calcium from whole foods.” Again, if you wish to continue any of these dietary changes, talk to a registered dietitian to be sure your nutritional bases are covered.

Although there’s a lot of social media backing for this diet, there’s not a lot of support from experts. “This diet plan is restrictive, complicated and can’t be sustained long-term — it’s not even meant to be followed beyond 30 days,” Davis says. “I always recommend that my patients find a diet that works for their entire life that can be personalized to them.”